A Simulation Study of Schemes for Block Loss Reduction in ATM Networks using FEC and Buffer Management

摘要

Traditional approaches to guaranteeing Quality-of-Service (QoS) in ATM networks have focused on performance metrics such as cell loss probability, end-to-end cell delay and delay jitter. However, the block loss rate is a more meaningful metric for applications such as medical imaging and real-time video, and for high-level protocols such as IP which will use ATM as the transport mechanism. A block is defined as a group of consecutive ATM cells. A block loss occurs when a single cell from a block is lost. We propose and evaluate, via extensive simulation, a technique for reducing block loss in ATM networks. Our method combines two well-studied approaches for minimizing the impact of information loss during transport over ATM networks which have been considered independently of each other in the past: priority-based cell discarding and Forward Error Correction (FEC). We also study an enhanced buffer management algorithm which we call Adaptive Pushout (ADP) that accounts for correlations between cell losses. The ADP algorithm reduces block loss rates to near-optimal levels. We consider further performance enhancements to the ADP policy that deliver excellent performance even under very heavy load.